1. Field of the Invention
The present invention generally relates to an alignment mechanism for aerosurface deployment systems. More particularly, it is concerned with a new and improved apparatus for independently adjusting deployable aerosurfaces in both the stowed and deployed positions.
2. Description of the Prior Art
Accurately positioning deployable aerosurfaces, such as wings or fins, in both the stowed and deployed positions can be important for optimum aerospace vehicle performance. For example, the wings of certain missile systems must be accurately aligned and stowed for launching purposes from an aircraft or a launch tube, and then deployed to an open position while the missile is in free flight. During captive carriage, the wings must be precisely positioned to interface with the carrier, such as an aircraft bomb eject rack. In free flight, precise, symmetric wing sweep angle is critical for aerodynamic performance.
Because prior art aerospace vehicles typically employ a single actuator for deploying two or more aerosurfaces, the aerosurfaces generally do not operate independently of each other. For example, in a missile system having a pair of wings, the movement of one wing a certain amount results in the other wing moving a corresponding amount; if all linkages and pivot point locations are perfectly aligned each wing position will be a mirror image of the other. However, if any linkages or pivot point locations are not perfectly aligned, the wing positions will be unsymmetrical due to an accumulation of dimensional tolerances.
It is relatively easy to adjust the sweep angle of each deployable aerosurface when the actuator, common to all the aerosurfaces, is fixed in a deployed configuration. For example, the lengths of the pushrods which connect the common actuator pushrod to their corresponding deployable aerosurface horns can be adjusted so that the deployable aerosurfaces are positioned to their desired sweep angles. Accordingly, when the deployable aerosurfaces are retracted to their stowed positions and the geometry of the entire kinematic system is perfectly aligned and positioned, the deployable aerosurfaces will be positioned to their designed stowed sweep angles. Any deviation from the theoretically exact orientation of the kinematic system components, however, will introduce error into the stowed aerosurface sweep angle. Each of the manufacturing tolerances that impact the geometry of the kinematic system, such as pivot axis locations, actuator alignment, or wing horn moment arm lengths, must be relatively small such that the summation of all the deviations will not result in positioning the deployable aerosurface outside the designed geometric envelope. It should be noted that if the stowed deployable aerosurfaces are readjusted for orientation in their designed stowed positions, the deployed positions will then be different and may fall out of the designed geometric envelope. Moreover, the adjustment of the deployed position directly influences the orientation of the stowed position.
Precise stowed and deployed aerosurface positions have previously been achieved by controlling the manufacturing tolerances that impact the geometry of the kinematic system. This approach has proven to be difficult and costly due to the number of tight tolerances involved. As the manufacturing tolerances become more stringent, the associated production costs increase rapidly.